This invention relates to simulators and, more particularly, to a missile system simulator for a TOW missile system in which the infrared source on a TOW missile is effectively simulated as well as target dynamics, launch platform dynamics, battlefield backgrounds, and atmospheric conditions.
As is well-known, TOW missile systems have been developed for both ground based and airborne applications. As these systems have proliferated, the need for training personnel in their usage has become increasingly important. Because of the amount of time required to train large numbers of people, and the attendant cost, it has become increasingly important to provide a training program which does not actually require the firing of a TOW missile. Further, adequate training involves training one to aim, fire, and guide the missile to a target under different sets of conditions, e.g. day, night, clear, obscure, the presence of countermeasures, etc. As a practical matter, it is not always possible to produce these various conditions in the field; or, if it were, the time and cost required for a training program could be prohibitive.
In response to the foregoing, numerous attempts have been made to develop TOW system simulators. A prime requirement for these simulators is that they be "hardware-in-the-loop" simulators that simulate various targets against different backgrounds with various atmospheric conditions and utilize actual system hardware in the simulation. The simulators also need to simulate the missile signature both during the initial launch phase and as it moves downrange. In this regard, it will be understood that in the initial launch phase, the signature corresponds to a plume of exhaust (a "butterfly" pattern) created by the firing of the missile's engine and emanating from the sides of the missile. After the missile's fuel is spent, the signature is provided by an infrared beacon whose radiation is received by a forward-looking-infrared-receiver (FLIR) located with the missile launch and guidance equipment. Lastly, the simulation needs to be a "real-time" simulation which enables the trainee to learn to react to what happens as he acquires a target, shoots a missile at it, and guides the missile to the target.
Some existing simulators employ digital simulations in which targets are superimposed upon simulated backgrounds. A radiance map is then generated and projected through an atmospheric model to create a second, or received radiance map. These simulators typically also incorporate a model of the FLIR itself, thereby producing a direct video output which the trainee views. Unfortunately, modeling of the FLIR compromises the effectiveness of the simulator. Approaches have been investigated as to how the FLIR can be properly simulated to provide comprehensive "hardware-in-the-loop" simulation. Among these are martricees of laser diodes, large arrays of variable resistors, a fixed map positioned in front of a heat source with the map having different hole patterns (number and sizes) to, in effect, create a radiance map.
Problems are associated with each of these alternative approaches. For example, diode arrays are complex to drive, and, because approximately one million (1,000,000) diodes may be needed to replicate a scene, expensive. A similar problem exists with the use of resistors. In addition, resistors create a thermal lag problem which is significant when trying to simulate the dynamics of missile movement in real-time. The dynamic range of both diodes and resistors also makes it difficult to simulate targets and missiles on the same array board.
Besides the above, other approaches to simulation could consist of using high-powered lasers which create simulated "hot spots" on a background which is positioned on a table or other support and mechanically moved about. The "hot spot" thus would be viewed as a blob of light corresponding to the infrared signal from the missile beacon, as received by the FLIR. Usually, however, these arrangements are big and cumbersome, prone to breakdowns, not very authentic from a training standpoint, and difficult to modify.